Method of rendering water-wettable solid material water repellent and product resulting therefrom



- ing the general formula:

Patented Aug. 26, 1952 METHOD, OF RENDERING WATER-WET- TABLE SOLIDMATERIAL WATER RE- PELLENT AND PRODUCT RESULTING THEREFROM "Arthur J.Barry, Midland, Mich., assignor to The Dow. ,Chemical Company, Midland,Mich., a

corporation of Delaware No Drawing. Original application December '10, t

1943, Serial No. 513,746. Divided and this apr 'ji plicatlon January 31,1946, Serial No. 644,654 v j i r":

15 Claims. (01.117-443) l 1 This invention concerns the treatment ofsolid hydrophilic materials with certain organo-silicon esters forpurpose of modifying a surface of the normally hydrophilic material andrendering it repellent; to water. It also concerns the resultantwater-repellent solid products.

, The organo-silicon esters employed as treating agents are disclosedand claimed as new compounds in acopending application Serial No.513,746, filed December 10, 1943, of which this application is adivision, which copending application was issued on August 20, 1946, asU. S. Patent'No. 2,405,988. They are compounds hav wherein R in eachinstance representsa'radical selected from the class consisting ofhydrocarbon and hydrocarbonoxy radicals and at least one R representssuch radical containing at least 8 carbon atoms and selected from theclass consistingof alkyl and alkoxy radicals, R represents a hydrocarbonradical and nis-an integer not greater than 3. When, in the aboveformula, n] is "greater than 1, the radicalsrepresented by the symbols Bmay be the same or different and, when n is aninteger less than 3, theradicals repre-, sented by the symbols B may be the same or different.Illustrative examples of organo-silicon esters having said formulaareoctadecoxy-dodecoxy propoxy silicon acetate, di-octadecoxypropoxy-silicon acetate,- tridodecoxy silicon formate, etc.These and other esters having the above formula will be discussedindescribing the invention. A r

- The organo-silicon esters having the above gene eral formula vary frommobile liquids to waxlike solids. They may be hydrolyzed with water toremcve the ester radicals and form organesilicols; which oftenundergointermolecular condensatlon reactions to form viscous liquid or solidproducts ofhigh molecular weight; or they may be reactedwith hydroxycompounds, e. g. alcohols, phenols, or cellulose, to form correspondingalkoxy-silicon derivatives of such hydroxy compounds.

The organo-silicon esters provided by the in-- vention are especiallyuseful as agents for the treatment of solid hydrophilic materialsparticularly cellulosic materials, to modify the surface thereof andrender such,materialsrepellentfto water. In a copendingapplicationserial No; 513,745 filed December 10, 1943, now, Patent No.2,469,625, it is disclosed that o'rgano-silicon hal ides maybe appliedto andreacted withthehydroxyl groups at thesurface of solid hydrophilicmaterials, e. g. metals, glass, wood, or cellulosic substances, tomodify the surface of such normally hydrophilic materials and renderthem re pellent to water, It is well known that such solid materials, asthey are ordinarily obtained, have reactive groups, e. g. hydroxylgroups, at their surface, and that the presence of such groups at thesurface of metalsis due to the fact that the metals undergo a slightdegree of oxide-- .tion on exposure to air, particularly moist-airHowever, in said copending application it is taught that the hydrogenhalide formed in the treatment tends to act upon and weaken cellulosicmaterials and that in treating the latter with organo-silicon halidescare should be taken to remove the hydrogen halide as soon aspossible soas to limit the destructive action which takes place. a r I l I have nowfound that the organo-silicon esters having the general formulahereinbef'ore mentioned may similarly be employed for the treat! ment ofhydrophilic solid materials to modify the surface of the latter andrender it repellent to water. In such treatment the orga'no-siliconesters apparently react chemically with hydroxyl;

groups at the surface of the hydrophilic material; to liberate anorganic carboxylic acid and chair. ically aflix organo-silicon radicalsto the hyd o-- philic base member. The reaction is accelerated} anddriven toward completion by. heatin and. the treatedbase member isadvantageously heated;

to promote formation and, preferably, evolution of the carboxylic acid.However, the invention is not limited to this theory as to the reasonfor the result which is obtained. The water-repellent film which isformed at the surface of the base member is very thin, and theappearance of the base member is usually not altered. The waterrepellentfilm thus provided on a normally hydrophili'cibase. member .isabsorptive to organic liquidsj Paints, varnishes, Iacquersand the likeusually adhere more firmly to such film than to the hydrophilic basemember itself; hence, the latter may advantageously be-provideli withsuch film prior to being painted or varnished.

The organo-silicon esters may be applied-tea variety of normallyhydrophilic solid materials, e. g. iron and its alloys,magnes'iumzandiits alloys, other metals, wool, wood, cotton,iorcellulose'esters 4 ene chloride, or propylene chloride, etc. It appears,therefore, that such ultimate failure of the water-repellent film formedby the higher organo-silicon esters of this invention is not due todestruction of the film but, more prob-ably, to a change in theorientation of the organo-silicon groups at the surface of thehydrophilic base member and that the subsequent washing with :an organicsolveht causes are-orientation of such groups so as to again render thetreate'dmaterial .uniformly repellent to water. The invention is, ofcourse, not restricted by this theory as to the reason' 'forthe-resultsobtained. In general, the ,perman-enceand durability of theWater-repellent filmsgfzormedratpthe surface of hydrophilic basemembers'increases with increase in the number of g-carbon atoms inthelargest alkyl or alkoxy' fradicala'tt ached' to the silicon atom of theoror ethers, etc., to modify surfaces of such materials and render themwater-repellent. .Apparently all such hydrophilic materials havereactivegroups, usually hydroxyl and" inssomei instances,

e. g. with wool, amino radicals, at the surfaceso;

that in all such treatments a chemical reaction may occur .withresultantbonding Q1 organo-.-silicon. 'li. dicals .toithe "surface of.the LhydrQLihiIic material underlt ieatment. 'IThat chemical bondlngprobably does '.take .,place is evidenced .hy the tact that the treatedmaterial .does not ,rea'dily ose its water-repellent propertie whenwashed withcsolvents .{for .the lQrgano-silicon .ester .,employedinthe'treatment. f

vIiflre ,organo s'ilicon esters .maybe applied .with particularadvantage .to ,cellulosic .m-aterials .such .wood,cotton,leelluloseiacetate or .ethyl. cellu lose-eta, since.theorganic,carboxylicacid which isfliberatedby the treatment has little.or

detrimentalaction on cellulos'icmaterials; hence, specialprecautions;for-rapidlyremoving the acid visiormedtare :not required.For this reathe organ o-gsilicon 'IBSTtBIS of this invention are upeiior ,to organo-silicon .halides :as agents for i treatin ,cellulosic:;.materials to rend-er rthem waterrepellent. e

r ifllheirequirementr that :therorgano-isilicon esters containion '1 thesilicon atom .at least :one :alkyl or :alkoa'cyzradicalih-avingrii'orzmore .tcarb on atoms is &mpoi'tant; since I hav e found that thepermahence 3,113. :durability of the .wa'ter repellent film which isformed :at the surface :o'f aihydrophilic material when the latter is"treated with such ester is largely dependent on the length of th'elargest alkyl or :alk-oxy-radi'cal attached to the sl licon-atom ofitheester. 'For instance, a 'hydro-i prime material such as potton may berendered water re'pellentby treatment with a lower -or-' gazrosiliconcompound such as triethyl-silicon acetate, triethozy-silicon acetate,tripropoxysihcon'acetate, tri-isoprop o-xy-silicon acetate,tribeams-satin acetate, 'or -dimethy'l sil-icon' dichloride, etc, butthe water-repellent film which .isiformed -;is :readily removedby-washing, particularlywithsoapy'water. In contrast, the higherorganp-silicon esters provided by the invention, whee applied to cpttonor other hydrophilic materia ls form a far -more permanent-and durablewaterrpellerit film which isnotreadilyremoved' gano-siliconester used informing uch film and theomano-silicon esters containing such alkyl oralk-oxyigroup having at least 12 carbon atoms are preferred forthepurpose.

"The-organo-silicon esters may be prepared by the reaction of a salt ofan organic carboxylic acidwith :a .highenorgano-silicon halidecorrespending :to :the ester product :desired. 'zMethods for makingorgano -silicon-h=alides arewellknown, but, :since many .of Cth-e higher:organo-silicon halides :used in preparing .the esters-anathemselves newcompouridszthe general :meth-ods.zfor making the halides will-'be."m-entione'dcbrie'fiy. Alkyl siliconrhalidesse. g. "octylssilico-n.trichloride or tri-dodecyl silicon chloride, ietc., ;may be :pre-'pared 'by reacting an salkylximagnesium :halide; e. g. octyl magnesiumchloride or dodecylemag-'- nesium bromide with a silicon tetrahalide,'e.*'g. silicon tetrachloride. Usually an ether' is :used as a mediumfor the reaction. 'Thereactants are preferably employed inapproximatelythe stoichiome'tric proportions'aand the product is purified bydistillation. Alkoxy silicon halides may bepreparedhy reacting-analcohol, e. g. octyl alcohol "or dodecyl fal-cohol, :With 'apolyhalo-silion DOUIIdISllChIaSTSiIiCDII tetrachl'ori'de,silicon"tetrabromide, ;diethyl-.silicon zdichloride, or phenyl-silicon'tri'chloride. fiuchreaction .usually occurs "readily at roomtemperature or :below and maybe carried out nearly quantitatively .byheating the mixture, e. g. to 100" 0., after' the initial vigor *of-the'reaction has' subsided.-' The reactants are employed in proportionssuch "as to replace at'least one, butno t all,--of the halogen atoms ofthe polyhalo-silicon compound -with alko-xygroups. For instance,'tridodecoxy silicon chloride may be prepared by reacting-'3molecular-equivalents o-f dodecyl alcohol with oneamole' of silicontetrachloride and 'di-dodecyl-do'decoxy silicon-chloride maybeprepared-by the reaction of equimolecular amounts'of dodeoyl alcohol anddi-do-decyl-silicon dichloride. Usually, 1a. solvent such as benzene,'ligroin, -or petroleum ether is used as a reaction medium and'themixture "is cooled,e.'g. to 10 C. or lower, in the early stageso'f'thereacti'on.

The organo-sil'icon esters employed as I hydrophobingagents arepreferably prepared by treating an orga-no-silicon halidahaving'on-thesilicon atom an alkyl or'alkoxy group containing at'least 8 carbonatoms, witha metal-salt of an organic carboxylic acid-and heatingthemixture to areaction temperature. Examples of organo-silicon halideswhich may be employed as reactants are octyl-silicon -trichloride,-decyl-silico'n trichloride,

di-oc'tyl-s'ilicon -'dichloride,

' tri-=dodecylsilicon chloride, di-myricyl-silicon dichloride, octyl'oxysilicon-trichloride, di-octyloxy-silicon dichloride,

tri-octyloxy s'ilic'on chloride,-dodecoxy-silicon trichloride,'phenyl-octyl dodecoxy-siliconchloride,---

d-i-dodecyl-dodecoXy-silicon chloride, dodecylmyricyloxy-silicondichloride, etc. In-place of the chlorides" the corresponding organo-silicon bromides may be used. Among the various salts of organiccarboxylic acids which may be used asr'eactantsare' sodiumformate,"potassium ace-- the present invention are high-boilingcompounds which tend to undergo decomposition-when fractionallydistilled; i V The following examplesdescribe anumberi of 5 ways'inwhich theprincipleof the invention has -been applied, but are ,not to beconstrued as tate, sodium propionate', potassium butyrate, so i 1 diumvalerate, sodium crotonate'ysodium oleate, sodium .stearate, sodiumbengzoate, or sodium cin- 1 namate, EtCHf Salts of polycarboxylic acidsmay] similarly be used to form neutral organo-silicon estersthereof. 1The salt is employed in amount at least as great as, that theoreticallyrequired to displace the halogenatomsof the organo-siliconhalidereactant and it preferably is'used in excess;

Usually; two chemical equivalent weights or more of the salt isused per:atomic weight? of halo in the organo-silicori halide reactant.- Inplace,

of the salts ofthe carboxylic acids, the free acids may, though somewhatless conveniently, be used as reactants. "One part by volume or moreofjan inert organic solvent such asgpetroleum ether," ligroin, benzene,or toluene, etc, is preferably,

f iting theinvention:

j h EXAM LE 1 In-each of a series of experiments, ahigher organo-siliconester was prepared by heating a,

' mixture of a sodium salt of an organic carboxylic acid and asolutionfof an orga'ho-silicon chloride in an equal volume ormore,-'us'ually about 51.5

parts by volume; of petroleum ether, or toluene,

under reflux at about 100 C. until the forma; tion and precipitation ofsodium .chloridewasE no longer observed injmost instancealfi hours: ofheating at said temperature wassufficient. The

mixture was then filtered to remove thesodium j chloride formed in thereaction, afterwhich the solventwas distilled from the filtratetoobtainthe organo-silicon ester product as theflresiduel' In some instances afurther quantity of the sol- 1 vent wasaddedprior to the filtration.inorden to dissolve the ester product, but usually the employed, perpart of the orgaho -silicon halideg as a medium for the reaction, butthe reaction may be carried out in the absence -of- *such medium.

The mixture" is heated underrefiux, orin a closed container, "to areaction temperature, us-

for completion of the reaction. Reacti0n temperatures" below ordabovethose just mentioned maybe used. The reaction is usually completeafter-from lofto 20 hours of heatingjat about:

quantity of solvent employed as the reactionmedium was sufficienttomaintain the product in solution; *Many'of the organo-silicon esterprbdtional distillation, but some of the products were of too highboiling point tojpermit distillation without the occurrence ofdecomposition. In all instances, the products were obtained ina highlyobtained in a concentrated, or substantially pure, i

form. In some instances, the product rnaybe'fur' thel purified hyrract-idnai "arsenal-ion under concentrated form satisfactory for use inthe treatment of fabrics or other solid hydrophilic materials to rendersuch materials'repellent to water. The following table names thereactants employed in preparing each organo-silicon ester product,states the. molecular proportions which they were used, describes theester proda.

not, and states vhether the product was distilled. Since many of theorgano-silicon halides em ployed in preparing the ester products arethemselves new compounds, the table includes a state?- ment as to thekinds and proportions of reactan used. in mal ring such halides. I'lheprocedures formmaking the organo silicon halides Thaye been, presentedin the foregoinegener'al description vacuum, but many of the qrganosilicon esters of of the invention.

1 Products believed to contain compounds formed by loss of one or moreacetate radicals.

ucts thusobtained werefurther purified by. free;

, flawed-Continued.

in ieahl'dffa series of experiments, a strip of iittofi bldadolo'thhalting '8, count (if '80 x 160 threads inch, wasim'mersed for '10minutes ina solution containing 3 per cent by weight of the .org'ano'silicon "ester named in Table II dissome i n i'a dry-cleaning'liquidconsisting of a mixture of ethylene chloride and propylene ch10- flde."The cloth wasfthe'n pressed with a 'flatiron heatedtoabout 250 C. untilsubstantially free df'the drycleaning fluid'and thereafter for about twomin tes to "assure reaction of the organesilicone ferjonftlie fabric.Different strips of the "treated cloth were subjected to different kindsof washing operations, after which each liquor, and testedfor'waterrepellency by the pellency toward water of each treated fabricin terms of the hydrostatic pressure in centimeters of water whichthefabric withstood'befored aka'ge occurred during the "test of thefahrifibythe 'above mentioned hydrostatic method.

hydrostatic method described by Slowinske in AmflDyestuffRporter 30 '7(1941). The kinds of washing operations employed in the difierent 7experiments are named in the table and are as follows: (1) A handwash'with water which contained 0.5 per cent by weight of 'soap (thehand soap marketed as Palmolive was used), and (2) subjecting thetreated material to extraction r'for From a comparison of Run 4 of TableII with Run 8 and "of Run '5' with Run 7, it will beno'ted that thewater-repellent films rbrme'a on fabrics by treating the latter withhigher alkyl silicon esters are somewhat more eife ctive and Trnorestableagainsttheaflion of soapy waterthan are the films formed bytreatingiabrics with correspondingalkoxy silicon esters.

nseam Anurnber" of trip 'Yof .cottorihroadcloth, havum.ors'o' xilso'r lraespemnc were ithldodecylf d i-phenylsilicon acetate, orodecyllflsilicon'acetate,and the treated ifab ridw'ere p'ss'edwithjaheatedjflatiron, as "1 However, the different pieces oftreated fabric were then subjected to washing procedures which were.even .more,sev'ere than those empmye'dm Example 2. One ofthe washingprocedures was the standard soap and water washing operation-describedon page 1'70 of the AATCC book of Standard Test Methods. Anotherprocedure involvedsubjection of a fabric .to extraction for,approximately .18 hours in a Sohxlet extractor while usingthe-dry-cleaning fluid mentioned in EXampleZ asthe extractant and then"freeing the fabric of the dry-cleaning fluid and subjecting it to saidstandard washing operation with soap and water-. A third procedureinvolved extracting a fabric with the dry- 'claningfluid and then"subjecting it -to the standard washing operation with soap and water,as just describedand next again subjecting it to extraction "with-"the;"drycleaning fluid for a periodoi about 18 hours in aSohxlet extractor.A treated fabric, after being washed by one of these three procedures,was dried and tested for water repellency by the hydrostatic methodmentioned in Example 2. Table 111 names the alkyl silicon esters usedfor the treatment of fa'brics in the different experiments and gives thewater repellency of the treated fabrics after being subjected to therespective washing procedures just described. The water repellency isexpressed in terms of the hydrostatic pressure, in centimeters of Water,which the fabric withstood before leakage occurred.

Table III of the water-wettable material is "12 carbon atomsand selectedfrom theclass co zn sisting of alkyl and alkoxy radicals, R repre-"sents ahydrocarbonradical, and n-is-an integer not greater than-3, andheating the trea'tedwater- -wettable material to a temperature atwhi'ch'a carboxylic acid is evolved, whereby thesurface rn'odified'an renderedrepellent to waterf 2.-'A method which -comprises contacting a solid 3cellulosic material with an or no-silicon compound having the generalformula MS ('Q- ')4-h .531 3L .1 wherein R in each-instance represents aradical selected from the class consisting offhydrocarbon andhydrocarbonoxy radicals 'and at least one R represents su'ch radicalcontaining' at least 12 carbon atoms and selected fromthe-classmasisting of alkyl and alkoxy radicals", R repr a hydrocarbonradical, and n is an integer greater than 3, and heating the'treatedcellulosic. material to a temperature-at which a carboxylic acid isformed,whereby the "surface of thecellulosic material is modifiedandrendered epelflenttowater.

3, Amethod which comprises applying to the surface or a water-wettablesolid; material, an organo-silicon compound having the general formula:1

wherein R in each instance represents a radical selected from the classconsisting of hydrocarbon and hydrocarbonoxy radicals and at least one Rrepresents such radical containing at least 12 carbon atoms and selectedfrom the class con- H2O Repellency of Treated Fabric After:

Organo-Sillcon Ester std. S p

and Water Wash Dry-cleaning Followed by Std. Soap and Water WashSuccessive Dry-cleaning;

Std. Soap and Water Wash;

Dry'cleaning Dodecyl-di-phenyl-silicon acetate 14 Tri-dodecyl-siliconacetate 19 From the above data it appears that the drycleaning fluid hasthe effect of orienting the organo-silicon radicals at the surfaces ofthe fabric so as to increase the repellency toward water.

Other modes of applying the principle of the invention may be employedinstead of those explained, change being made as regards the step orsteps herein disclosed provided the step or steps set forth by any ofthe following claims or the equivalent of such stated step or steps beemployed.

I therefore particularly point out and distinctly claim as my invention:

1. A method which comprises applying to the surface of a water-wettablesolid material, an organo-silicon compound having the general formula:

R,.si -o-- "3R')l-n wherein R in each instance represents a radicalselected from the class consisting of hydrocarbon and hydrocarbonoxyradicals and at least one B represents such radical containing at leastR,,si -o-tR' i wherein R in each instance represents a radical selectedfrom the class consisting of hydrocarbon and hydrocarbonoxy radicals andat least one R represents such radical containing at least 12.

carbon atoms and selected from the class consisting of alkyl and alkoxyradicals, R represents a hydrocarbon radical and n is an integer notgreater than 3, heating the treated cellulosic material to a temperatureat which a carboxylic acid is evolved, and thereafter contacting thetreated cellulosic material with an organic liqllisli ana lei dissqvinathe r anm ilic o mimd ha inathe above. g nera rm a- 5 Awater-repellent-solid article; prepared by 5911396; treatment; of. a;solid wa er=wet a ba member, in-accordanc with the method of claim 1.

solid watc -repellent cellulosic article prepared by the methoclof claim2.

method 7 as claimed in; claim 2, wherein Q RQU menQ- HWQ .cnm una w c ised as a fi n mat rial siw tadec x i i on acetate.

8. A solid water-repellent cellulosic article prepared by the methodof'claim '7.

, ;9;.; A method; asclaimed in claim 2, wherein .the organo-siliconcompound which is employed as a starting material is ,onehavingthegeneral -fprm la given inclaim 2 and having, attached tly tothesilicon atom ofithe molecule, an aqical which-contains at leastlZ,carbon 1 A, soli terfle e l t e losic a ti le "pr-e airegl bythamethodof claim9.

13. A solid water-repellent cellulosic article prepared by the method ofclaim4.

14. The methodwhichcomprises contactinga d. e os t ri l w h rird s cc iicbn acetate and. heating the treated cellulosic maiterialto atemperature at'which' a carbog ryli'c acid is formed, whereby 'thesurface ojj the 1cel;- lulosic material is modified and renderedre e 1;-lent to water.

l w e -r ell l ulosic i ilc reparedby emethodnrl la m :4;-

REFER NCES CI ED: The following: references are of recor d in the fileof-thi's patent:

' vNnEn'smfrE mmms;

1. A METHOD WHICH COMPRISES APPLYING TO THE SURFACE OF A WATER-WETTABLESOLID MATERIAL, AN ORGANO-SILICON COMPOUND HAVING THE GENERAL FORMULA: